This circuit is from a 1976 Motorola CMOS manual. It can be implemented with modern Darlingtons like those in the Texas TIP series. The load current depends only on the Darlington transistor.
This circuit is from the 1972 Linear Data Book of RCA, but it can be made with more modern...
I found this simple circuit from an English magazine from 1984. The circuit can be easily...
We found this logic level tester in a 1976 documentation. The circuit is powered by the voltage of the...